Add more UMA in CopylessPasteExtractor

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index cbc2af415e46b6e89b2edfe137c5060f9b031328..a71ce76f52b21c77f0b0075947ef147a8504e1b7 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -9148,12 +9148,26 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <summary>For each cookie added to the store, record it's type(s).</summary>
 </histogram>
 
+<histogram name="CopylessPaste.ExtractionFailedUs" units="microseconds">
+  <owner>wychen@chromium.org</owner>
+  <summary>
+    The time spent on scanning the document in the main frame to extract the
+    metadata. The metadata would be used to feed Icing for CopylessPaste feature
+    on Android. This only counts pages with failed or empty JSON extraction.
+  </summary>
+</histogram>
+
+<histogram name="CopylessPaste.ExtractionStatus" enum="ExtractionStatus">
+  <owner>wychen@chromium.org</owner>
+  <summary>The error status of metadata extraction for AppIndexing.</summary>
+</histogram>
+
 <histogram name="CopylessPaste.ExtractionUs" units="microseconds">
   <owner>wychen@chromium.org</owner>
   <summary>
     The time spent on scanning the document in the main frame to extract the
     metadata. The metadata would be used to feed Icing for CopylessPaste feature
-    on Android.
+    on Android. This only counts pages with successful JSON extraction.

[Ilya Sherman, 2017/04/12 23:25:55]

Was this always true, or is this a change in semantics?  If it's a change in
semantics, then please rename the histogram, so that historical data with
different semantics is separated off from the new semantics.

[wychen, 2017/04/12 23:40:04]

The feature is not launched yet, and we haven't collected any data. In this
case, I guess changing the meaning should be fine.

   </summary>
 </histogram>
 
@@ -93258,6 +93272,14 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <int value="2" label="Cache entry validators don't match request"/>
 </enum>
 
+<enum name="ExtractionStatus" type="int">
+  <summary>The status of metadata extraction for Appindexing.</summary>
+  <int value="0" label="OK"/>
+  <int value="1" label="Empty result"/>
+  <int value="2" label="JSON parsing failure"/>
+  <int value="3" label="Wrong type in JSON top-level object"/>
+</enum>
+
 <enum name="Exynos5250LotIdEnum" type="int">
   <int value="0" label="Fused device"/>
   <int value="1" label="Generic unfused device"/>